Telephone



(N0 Medal.)

. A. E. DOLBEAR.

TELEPHONE.

Patented Nov. 13, 1883.

Wkqasses UNITED STATES PATENT UFFIGE.

AMOS E. DOLBEAR, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGXMENTS, TO THE DOLBEAR ELECTRIC TELEPHONE COMPANY, OF

new JERSEY.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 288,215, dated November 13,1883.

Application filed May 31, 1880. (N model.)

To all whom, it may concern.-

Be it known that I, Amos EMERSON Don BEAR, of Someryille, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Telephones, of which the following is a specifica tion.

My invention consists in the combination, with two coils on the same core, of two transro mitters and two batteries or equivalent generators, one in circuit with each coil.

In the accompanying drawing I have illustrated one form of my invention as used to transmit speech and other sounds.

I 5 X is one transmitter, the wires in a of which form part of a circuit in which is coil F on core. Y is the other transmitter, its wires being parts of a circuit in which is another coil, G, on the same core. Each 'circuit contains a suitable generator of electricity. With each coil thus providedwith a generator for supplying its circuit with electricity, it is evident that either coil may be made primary or secondary'at pleasure. The circuit a F a X will be the primary and a G all the secondary when the electric current is varied by X, and vice versa when the electric current is varied by Y. 1

The coilsmay be arranged in any suitable way; but to best adapt transmitters to be used either as transmitters or receivers they should be so arranged as to afiect or be affected by the core to a like extent. \Vhen the circuits through the two coils connect two transmitters, as shown in the drawing, any variations of the diaphragm of one-such as caused by the human voice or other s0und-waves, or otherwise-will cause variations in the batterycurrent through its circuit and induce currents on the other circuit either like or contrary to the battery-current in that circuit, and thereby produce similar vibrations in the diaphragm of the other transmitter, which thus becomes a receiver.

I claim as my invention The combination of two circuits, each containing a battery, a coil, and a transmitter, with a core extending through both coils, as set forth.

AMOS EMERSON DOLBEAR.

lVitnesses:

J. E. MAYNADIER, J. R. Snow. 

